The present invention relates to a disk brake for a motor vehicle brake system having a frame-type housing, at least two brake pad arrangements, which are accommodated in the frame-type housing and between which a brake disk that is rotatable about an axis of rotation may be accommodated, and at least two guide bolts, which are mounted on the housing and on which at least one of the brake pad arrangements is guided with play in an axially displaceable manner.
Such disk brakes are prior art.
Thus, for example the document DE 103 12 479 A1, and corresponding U.S. Pat. No. 7,431,132 B2, both of which are incorporated by reference herein, describes a disk brake, in which brake pad arrangements are guided displaceably on guide bolts. One of the brake pad arrangements is displaced by means of an actuating piston in the housing. The entire disk brake operates according to the floating caliper principle.
For positioning brake pad arrangements inside a housing of a disk brake it is moreover customary to use hold-down springs for the brake pad arrangements. Such a hold-down spring arrangement is known from the document DE 199 35 036 C1. In this document individual brake pad arrangements in the housing are pressed by a bow-shaped spring down onto the guide bolts in radial direction relative to the axis of rotation of the disk brake. The guide bolts in this case penetrate recesses in the brake pad arrangements with play. It has however emerged that in dependence upon the magnitude of the braking torque acting upon the respective brake pad the brake pad arrangement may shift relative to the guide bolts within the existing play. This then leads to a phenomenon whereby at low braking torques the respective brake pad arrangement are pressed by the hold-down spring from above onto the guide bolts and held in contact therewith. However, as soon as the braking torque increases and an ensuing tilting moment in relation to the guide bolts acts upon the respective brake pad arrangement, a state is reached, in which the forces exerted by the hold-down spring on the respective brake pad arrangement are overcome and so the respective brake pad arrangement tilts. Finally the brake pad arrangement tilts within the play between guide bolt and guide bolt recess of the brake pad arrangement to such an extent that the edge of the recess strikes against the guide bolt. This striking may lead to undesirable noise, which is perceived by the driver of the vehicle and may convey to him the impression of malfunctioning of the brake system. The same applies to the situation, in which the brake is released, so that the braking torque is reduced more or less abruptly and because of the action of the pad-retaining spring the respective brake pad arrangement is moved back into its normal position. Here too, the relative movement within the play between guide bolt and guide bolt recess in the brake pad arrangement occurs and finally leads similarly to a noise-inducing audible striking of the guide bolt against the guide bolt recess.